JPH0982803A - Method and device for formation of via hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a high quality of via hole without changing the process of manufacture. SOLUTION: A thin film 23, which absorbs the second high harmonics(SH light) 8 of a flash lamp excitation Q-switch Nd:YAG laser, is formed on the surface of the insulating film 21 by irradiating the sample, coated with an insulating film 21 over a conductive wiring 22, with the fourth high harmonics(FH light) of a continuous excitation Q-switch Nd:YAG laser. The insulating film 21 on the lower part of this thin film 23 is removed by irradiating the formed thin film 23 with the SH light 8.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a via hole in an insulating layer between conductor lines of a large-scale integrated circuit (LSI), a liquid crystal display (LCD), or the like in order to correct a fine circuit pattern. A method and apparatus for forming.

[0001]

2. Description of the Related Art A method of forming a via hole after forming a wiring pattern for correcting the wiring of an LSI or the like is described in "Preliminary Proceedings of the 36th Joint Lecture on Applied Physics in Spring 1989 2p-L". -10 ". In this conventional via hole forming method, referring to FIGS. 3A and 3B, the surface of the conductor wiring 22 under the insulating film 21 is focused and irradiated with a laser beam 41, and the laser beam 41 on the surface of the wiring 22 is irradiated.
Via the process of absorbing, locally heating the surface of the wiring 22, and evaporating, and by using the pressure at the time of evaporation to blow off the insulating film 21 above the wiring 22, the via hole 42 is formed.

Further, by using a laser beam having a wavelength in the ultraviolet region which is absorbed to the insulating film to some extent and irradiating the laser beam on the surface of the insulating film, the insulating film is gradually shaved off from the surface. A method of forming holes is also considered. In this case, the processing laser light is the fourth harmonic light of the Nd: YAG laser or Kr.
Utilization of F excimer laser light or the like is under study.

Although different from the application example to LSI and LCD, when forming a via hole of a multilayer printed wiring board by laser light, a dye is mixed into the polymer layer of the insulating film to absorb the laser light. A method for promoting the above is disclosed in Japanese Patent Laid-Open No. 1-206698.

[0004]

However, in the method of forming a via hole by converging and irradiating a laser beam onto the surface of the conductor wiring, the explosive pressure due to evaporation of the surface of the conductor wiring acts isotropically. Greatly spreads around the irradiation spot of laser light. As a result, as shown in FIG. 3B, the processed shape becomes a mortar-shaped hole, and there is a problem that the processing quality is significantly deteriorated. In recent years, as the wiring of LSI has become multi-layered, the conductor wiring layer has come to be located deeper than the surface of the insulating film.
There is a marked tendency that the processed shape becomes a mortar shape. Moreover,
It is very difficult to control this hole shape.

Further, in the above method, it is necessary to increase the explosion pressure due to evaporation when the insulating film is thick.
Therefore, the irradiation intensity of laser light must be increased. However, increasing the irradiation intensity of the laser light may result in the loss of existing conductor wiring, and has a serious reliability problem.

On the other hand, in the method of forming via holes by irradiating the surface of the insulating film with laser light in the ultraviolet region,
Generally, assuming that KrF excimer laser (wavelength 248 mm) and fourth harmonic light (wavelength 266 mm) of Nd: YAG laser, which can be practically used as laser light in the ultraviolet region, are used as an insulating film in LSI or the like. Absorption of laser light into the silicon oxide film and the silicon nitride film is not sufficient, and it is not easy to realize processing with good shape controllability.

In addition, a method of forming a via hole by mixing a dye into an insulating film applied to a multilayer wiring printed circuit board and irradiating the portion with a laser beam is described as an LSI.
There is a serious problem in terms of processing reliability when it is applied to processing of LCDs and LCDs.

That is, in the LSI, the number of wiring layers is increased in order to improve the degree of integration, and as a result, the manufacturing process is complicated, so that the insulating film between the conductor wiring tends to be thin. Even if the thinned insulating film is used, various measures have been taken in order to provide sufficient insulating properties. Under such circumstances, mixing a foreign substance (dye) into the insulating film poses a serious problem in terms of reliability.

Further, in order to apply this method, L
It is necessary to change the entire process such as the step of mixing dye in the SI insulating film formation process. Considering the above-mentioned reliability problem, this method is extremely unrealistic. I have to say.

[0010]

In order to solve the above problems, a via hole forming method and apparatus of the present invention irradiate a sample in which a conductor wiring is covered with an insulating film with a first laser beam. Then, the via hole is formed by removing the insulating film, and in particular, a thin film that absorbs the first laser light is formed on the surface of the insulating film, and the first laser is applied to the formed thin film. By irradiating with light, the insulating film under the thin film is removed.

Further, the present invention uses a laser CVD technique as a method for forming a thin film which becomes an absorption layer of the first laser light on the surface of the insulating film.

Further, according to the present invention, when the thickness of the insulating film on the conductor wiring is large, the step of forming the thin film and the step of removing the insulating film under the thin film are repeated a plurality of times.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a first embodiment of a via hole forming method and apparatus according to the present invention will be described in detail with reference to the drawings.

In this embodiment, a via hole is formed by providing a laser beam absorbing layer for forming a via hole on the surface of the insulating film covering the conductor wiring and removing the insulating film by utilizing the heating action of the absorbing layer. To do.

FIG. 1 is a schematic view showing the apparatus configuration of this embodiment. A raw material for laser CVD, for example, chromium carbonyl (Cr (CO) 6) powder is accumulated in the reservoir 1. The chromium carbonyl powder is sublimed by being heated in the reservoir 1. The chromium carbonyl gas obtained by sublimation is mixed with the rare gas such as argon (Ar) gas as a carrier and supplied into the chamber 2. The flow rate of the carrier gas is controlled by using a mass flow controller (not shown).

In the chamber 2, the sample 3 is arranged on the heater 4. The heater 4 heats the sample 3 in order to balance the temperature of the sample 3 and the temperature of the supplied CVD source gas. Further, the heater 4 is mounted on the XY stage 5.

Flash lamp excitation Q switch Nd: Y
AG laser oscillator 6 or continuous excitation Q switch Nd:
The laser beam 8 or 9 emitted from the YAG laser oscillator 7 is transmitted through the slit mechanism 11 after the beam diameter is expanded by the beam expander 10, and the slit mechanism 1
Irradiation is carried out in such a manner that the opening image of No. 1 is transferred to the surface of the sample 3. By changing the opening size of the slit mechanism 11,
The surface of the sample 3 can be irradiated with laser light 8 or 9 having an arbitrary spot size according to the diameter of the via hole to be formed.

Then, the surface of the sample 3 arranged in the chamber 2 is irradiated with the fourth harmonic light (hereinafter, referred to as FH light) 9 of the continuously excited Q-switched Nd: YAG laser emitted from the laser oscillator 7. As a result, a chromium thin film can be formed on the surface of the sample 3. That is,
A chromium thin film is formed on the surface of the sample 3 by using the laser CVD method.

On the other hand, the chromium thin film formed on the surface of the sample 3 is irradiated with the second harmonic light (SH light, wavelength 532 nm) 8 of the flash lamp excitation Q-switch Nd: YAG laser emitted from the laser oscillator 6. Thus, a via hole can be formed in the sample 3.

The laser processing apparatus of this embodiment is
An observation system, for example, a microscope 12, a CCD camera 13, and a monitor 14 for observing the irradiation position of laser light and the processing state is provided.

Next, the method of forming via holes according to this embodiment will be described with reference to FIG.

The via hole forming method of the present embodiment comprises a first step of forming a thin film on the surface of an insulating film and a second step of forming a via hole by irradiating the thin film with laser light. Contains. In particular, the first step is
A thin film serving as an absorption layer of a laser beam for forming a via hole is formed on the surface of an insulating film by using a laser CVD technique.

Referring to FIG. 2A, in the sample 3 in which the via hole is formed, the insulating film 21 is coated on the upper part of the conductor wiring 22. As shown in FIG. 2B, as a first step, a continuous excitation Q-switch N is formed on the surface of the sample 3 placed in the chamber 2 filled with chromium carbonyl gas.
By irradiating the FH light 9 emitted from the d: YAG laser oscillator 7, the chromium thin film 23 is formed. The formation region of the chromium thin film 23 is set according to the diameter of the via hole to be formed.

Here, in this embodiment, the output of the FH light 9 is on the order of 0.1 mW / μm 2 on the sample surface when the Q switch frequency is 2 kHz. Also, CV
As the D source gas, the reservoir 1 is kept at 45 ° C. to generate chromium carbonyl gas (partial pressure of about 1 Torr), the chromium carbonyl gas is diluted with Ar gas, and then used at a vapor pressure of about 0.3 Torr. . Under such conditions, when the surface of the sample 3 is irradiated with the FH light 9,
It is possible to form the chromium thin film 23 having a thickness of about 1000 angstrom by irradiation for 4 seconds. Further, by driving the XY stage 5 and moving the sample 3 relative to the spot of the FH light 9, the thin film 23 formed on the surface of the insulating film 21 can be connected in a wiring shape.

The thickness of the thin film to be formed can be linearly changed within a predetermined range by increasing or decreasing the irradiation time or the laser output. Therefore, by selecting the optimum conditions, it is possible to form a thin film having a desired thickness in accordance with the thickness of the insulating film at the place where the via hole is formed.

Next, as shown in FIG. 2C, as a second step, a chromium thin film 23 formed on the surface of the insulating film 21.
Pulse width of 4 to 5 ms emitted from the laser oscillator 6
By irradiating the SH light 8 of
To form That is, the chromium thin film 23 formed on the surface of the insulating film 21 is an absorbing layer for the SH light 8, and the insulating film 21 under the chromium thin film 23 is removed by the heating action of this absorbing layer, and the via hole is formed. 24 is formed.

In this embodiment, since the via hole forming laser light (SH light) absorption layer is provided on the surface of the insulating film in advance, the laser light energy can be efficiently used, and the laser light irradiation area is obtained. Via holes having a diameter approximately equal to can be formed. Further, the shape of the via hole can be easily controlled by controlling the shape of the thin film formed on the surface of the insulating film.

The laser beam used in the first step may be a continuous oscillation or a repetitive pulse oscillation laser of the order of kHz, and the laser beam used in the second step may be a pulse with a high peak value. Any pump laser may be used.

Next, a second embodiment of the present invention will be described in detail with reference to FIG.

This embodiment is a method of forming via holes, which is preferably applied especially when the thickness of the insulating film covering the conductor wiring is large. That is, when the thickness of the insulating film is large, the SH light absorption layer is not formed by single SH light irradiation, but the SH light absorption layer forming step and the SH light irradiation are performed. The step of removing the insulating film is repeated a plurality of times to finally form a via hole.

FIG. 3 is a diagram showing a forming procedure of the via hole forming method of the present embodiment. First, as shown in FIG. 3A, FH is formed on the surface of the insulating film 21 covering the conductor wiring 22.
By irradiating with the light 9, the chromium thin film 23 which is an absorption layer of the via hole forming laser light (SH light) is formed by utilizing the laser CVD technique. Next, as shown in FIG. 3B, the thin film 23 is irradiated with the SH light 8 to remove the insulating film 21 below the thin film 23. Here, since the output level of the SH light 8 is suppressed to a level at which the conductor wiring 22 is not damaged, the SH light 8 is output once.
Unlike the above-described first embodiment, the irradiation of No. 1 does not open the conductor wiring 22. Therefore, as shown in FIG. 3C, a thin film 23 is formed again on the surface of the insulating film 21 remaining on the conductor wiring 22 by using the laser CVD technique by irradiation of the FH light 9 in the same manner as described above. To be done. Then, by irradiating the newly formed thin film 23 with the SH light 8 a second time, the via hole 24 can be formed as shown in FIG. 3D. Here, the step of forming the thin film 23 on the surface of the insulating film 21 and the thin film 23
The step of removing the insulating film 21 by irradiating the SH light 8 to the above corresponds to the above-mentioned first step and second step, respectively.

According to this embodiment, the via hole can be formed without increasing the SH light output even when the thickness of the insulating film covering the conductor wiring is large. It is possible to prevent damage to.

[0033]

As described above, according to the method and apparatus for forming a via hole of the present invention, the absorption layer for the laser light for forming a via hole is formed only in the region where the via hole is required to be formed. By irradiating the absorption layer with a laser beam for forming a via hole, the via hole is formed, so that a high quality via hole can be formed. As a result, the wiring of LSI and LCD is modified or reassembled. The reliability in work can be dramatically improved.

Further, the absorption layer is an LSI or LC.
Laser CV generally used in D manufacturing process
Since it is formed by the D technique, it is possible to easily form a high quality via hole without changing the manufacturing process.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a processing procedure according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a processing procedure according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a processing procedure according to a conventional via hole forming method.

[Explanation of symbols]

1 Reservoir 2 Chamber 3 Sample 4 Heater 5 XY Stage 6 Flash Lamp Excitation Q Switch Nd: YAG Laser Oscillator 7 Continuous Excitation Q Switch Nd: YAG Laser Oscillator 8 SH Light 9 FH Light 10 Beam Expander 11 Slit Mechanism 12 Microscope 13 CCD Camera 14 Monitor 21 Insulating Film 22 Conductor Wiring 23 Chrome Thin Film 24 Via Hole

Claims (5)

[Claims] 1. A method of forming a via hole by irradiating a sample, in which a conductor wiring is covered with an insulating film, with a first laser beam to remove the insulating film, the method comprising: A first step of forming a thin film that absorbs the first laser light on the surface; and a step of removing the insulating film under the thin film by irradiating the thin film with the first laser light. A method of forming a via hole, comprising the step of 2. 2. The first step is to irradiate a surface of the insulating film of the sample, which is placed in a compound gas atmosphere, with a second laser beam, so that a region irradiated with the second laser beam is irradiated. The method of forming a via hole according to claim 1, wherein the thin film is locally formed by a decomposition reaction of the compound gas molecule. 3. After the second step, when the insulating film remains on the conductor wiring, the first step and the second step are repeatedly performed at least once or more. A method for forming a via hole, which is characterized by the above. 4. An apparatus for forming a via hole by irradiating a sample, in which a conductor wiring is covered with an insulating film, with a first laser beam to remove the insulating film. A first means for forming a thin film that absorbs the first laser light on the surface; and a step of irradiating the thin film with the first laser light to remove the insulating film under the thin film. 2. A via hole forming apparatus, comprising: 5. The second means irradiates a surface of the insulating film of the sample, which is placed in a compound gas atmosphere, with a second laser beam, thereby irradiating the region irradiated with the second laser beam. Laser CVD for locally forming the thin film by the decomposition reaction of the compound gas molecule
The via hole forming apparatus according to claim 4, wherein the via hole forming apparatus is an apparatus.